(3E,5E)-3,5-Dibenzylidene-1-phenethylpiperidin-4-one

In the title compound, C27H25NO, the piperidine ring adopts an envelope conformation with the N atom at the flap position. The two benzylidene-benzene rings are oriented at a dihedral angle of 8.5 (1)°. In the crystal, the molecules are linked into centrosymmetric dimers by pairs of intermolecular C—H⋯O hydrogen bonds. The dimers are connected via C—H⋯π interactions involving the phenyl rings.

In the title compound, C 27 H 25 NO, the piperidine ring adopts an envelope conformation with the N atom at the flap position. The two benzylidene-benzene rings are oriented at a dihedral angle of 8.5 (1) . In the crystal, the molecules are linked into centrosymmetric dimers by pairs of intermolecular C-HÁ Á ÁO hydrogen bonds. The dimers are connected via C-HÁ Á Á interactions involving the phenyl rings.
Cg1, Cg2 and Cg3 are centroids of the C1-C6, C14-C19 and C22-C27 phenyl rings, respectively. Symmetry codes: (i) Àx þ 2; Ày þ 1; Àz; (ii) Àx þ 1; Ày À 1; Àz; (iii) Àx þ 1; Ày; Àz; (iv) x; y À 1; z.  and as synthetic intermediates. Biologically active alkaloids of the substituted piperidine ring system have been targeted for their total or partial synthesis. During a fairly recent 10-year period, several thousand piperidine compounds have been mentioned in clinical and preclinical studies (Watson et al., 2000). Selective inhibition of a number of enzymes involved in the binding and processing of glycoproteins has rendered piperidine alkaloids as important tools in the study of biochemical pathways (Asano et al., 2000). Piperidine derivatives are found to possess pharmacological activity and form an essential part of the molecular structures of important drugs such as raloxifene and minoxidil (Risi, 2008). A new neuroleptics has found that the piperidine derivatives have high affinity for CNS (Scriabine, 1980).
The bond lengths (Allen et al.,1987) and angles are within normal ranges.

Experimental
A mixture of 1-phenethyl-4-piperonidone (0.001 mmol) and benzaldehyde (0.002 mmol) were dissolved in methanol (10 ml) and 30% sodium hydroxide solution (5 ml) was added. The mixture was stirred for 5 h. After completion of the reaction as evident from TLC, the mixture was poured into crushed ice and then was neutralized with conentrated HCl. The precipitated solid was filtered, washed with water and recrystallized from ethanol to obtain the title compound as light yellow crystals.

Refinement
H atoms were positioned geometrically [C-H = 0.95 or 0.99 Å] and refined using a riding model, with U iso (H) = 1.2 U eq (C). Fig. 1